• Submitting single-player scores when played with more than one instrument. See this thread for full explanation.

• Double bass (be it a custom or a store-bought mod)
• Adjusting calibration settings to alter optimal paths

• Auto-kick

• Homemade mods to the guitar/drums/controller that involves taking apart the guitar, drums, or controller

• Easy-Expert
• Hacking of any kind (i.e. custom songs; an exact replica of a chart in Game_GuitarHero GH1∞ put into Game_GuitarHeroIIILegendsOfRock GH3∞ cannot be used for scoring)
• According to Deimos∞, Precision Mode is a cheat
• Submitting scores across systems (i.e. submitting a score you earned on 360 under Wii)
• Playing a non-modified song on a custom game (i.e., playing Song_GH2_FreeBird Free Bird∞ on a custom Game_GuitarHeroII GH2∞ game)

See Also

1. Cheat Codes

• Easy-Expert
• Stage Mode
• Large Gems
• Select Venue / New Venues Only
• Awesomeness Detection
• Performance Mode

• Switching controllers in the middle of a song (according to kuh-ray-zee this is just frowned upon. This is still under debate but for now...)

• No-Fail (legal if you want to prove cutoffs)
• Having someone else hold down a fret, strum, or hit select (guitar) or having someone else hit a pad or kick the bass pedal (drums)
• Hacking of any kind (i.e. custom songs; an exact replica of a chart in GH1 put into GH3 cannot be used for scoring)
• Pro-Face-Off Pro Face Off Mode∞. Scores that you get from PFO are considered illegitimate because you don't have to save SP for parts you would have failed otherwise. You must prove you can pass the whole song without SP before you can submit a PFO score.
• Glitches (i.e. the practice mode glitch in GH2.). Some glitches may be legal you should probably check with someone here though
• Submitting scores across systems (i.e. submitting a score you earned on 360 under Wii)
• Hyperspeed / Breakneck Speed
• Any thing that alters the appearance of your guitar or guitarist (i.e. air guitar)
• Using a non automated object to strum (i.e. a pick).
• Squeezing
• Playing keyboard style
• Playing a non-modified song on a custom game (i.e., playing Free Bird on a custom GH2 game)

• Using a standard controller

• Submitting a rounded or false score. Even rounding down is considered an illegitimate score.

What is and isn't cheating

What IS considered cheating:

• No-Fail (Legal if you want to prove cutoffs)
• Easy-Expert
• A Bot
• Using tape/rubber bands to hold down a fret
• Having someone else hold down a fret, strum, or hit select
• Hacking of any kind (ie Custom Songs. an exact replica of a chart in GH1 put into GH3 cannot be used for scoring)
• According to Deimos∞, Precision Mode is a cheat
• Pro Face Off Mode. Scores that you get from PFO are considered illegitimate because you don't have to save SP for parts you would have failed otherwise. You must prove you can pass the whole song without SP before you can submit a PFO score.
• Glitches (ie. the practice mode glitch in GH2.). Some glitches may be legal you should probably check with someone here though
• Submitting Scores across systems (ie submitting a score you earned on 360 under Wii)
• Submitting a rounded or false score

What is NOT considered cheating:

• Using a standard controller (Dualshock/Xbox Controller/Wii remote)
• Hyperspeed / Breakneck Speed
• Large Gems
• Any thing that alters the appearance of your guitar or guitarist (ie air guitar)
• Using a rubber band to fix your whammy bar
• Using any body part outside of the ordinary. You could strum with your dick for all i care, its legal
• Using Select to activate star power.
• Performance Mode
• Using a non automated object to strum (ie. a reeltar pick).
• Looking in a mirror for lefty flip (in league play this is considered cheating)
• A Hyperspeed towel
• Wearing gloves
• Using baby powder or other things to keep your hands dry
• Using grease or other things to keep your hands wet
• Squeezing
• Taping rubber to the strum bar (in essence this is basically wearing gloves)
• Playing Keyboard style
• Having someone make a path for you
• Playing a non-modified song on a custom game (ie, playing Free Bird on a custom GH2 game)

What is not considered cheating, but is frowned upon:

• Switching controllers in the middle of a song (according to kuh-ray-zee[?] this is just frowned upon. This is still under debate but for now...)

What you should go to the Hardware∞ forums about:

• Homemade mods to the guitar/controller that involves taking apart the guitar or controller

What we aren't quite sure about yet:

• Pausing in the middle of a song
• Using a drum pad (see FlorisJan's post∞) to play guitar